Decomposition Furnace Research Articles

The Co-Processing Combustion Characteristics of Municipal Sludge within an Industrial Cement Decomposition Furnace via Computational Fluid Dynamics

Dealing with municipal sludge in an effective way is crucial for urban development and environmental protection. Co-processing the sludge by burning it in a decomposition furnace in the cement production line has been found to be a viable solution. This work aims to analyze the effects of the co-disposal of municipal sludge on the decomposition reactions and NOx emissions in the decomposing furnaces. Specifically, a practical 6000 t/d decomposition furnace was taken as the research object. To achieve this, ANSYS FLUENT with a UDF (user-defined function) was applied to establish a numerical model coupling the limestone decomposition reaction, fuel combustion, and NOx generation and reduction reactions. The flow, temperature, and component field distributions within the furnace with no sludge were firstly simulated with this model. Compared with site test results, the model was validated. Then, with sludge involved, the structure and operation parameters of the decomposition furnace for the co-disposal of municipal sludge were investigated by simulating the flow field, temperature field, and component field distributions. Parametric studies were carried out in three perspectives, i.e., sludge mixing ratio, preheating furnace arrangement height, and sludge particle size. The results show that all three aspects have great importance in the discomposing process. A set of preferable values, including a sludge mixing ratio of 10%, preheating furnace height of 21.5 m, and sludge particle diameter of 1.0 mm, was obtained, which resulted in a raw material decomposition rate of 89.9% and a NO volume fraction of 251 ppm at the furnace outlet.

Optimizing Temperature Setting for Decomposition Furnace Based on Attention Mechanism and Neural Networks.

The temperature setting for a decomposition furnace is of great importance for maintaining the normal operation of the furnace and other equipment in a cement plant and ensuring the output of high-quality cement products. Based on the principles of deep convolutional neural networks (CNNs), long short-term memory networks (LSTMs), and attention mechanisms, we propose a CNN-LSTM-A model to optimize the temperature settings for a decomposition furnace. The proposed model combines the features selected by Least Absolute Shrinkage and Selection Operator (Lasso) with others suggested by domain experts as inputs, and uses CNN to mine spatial features, LSTM to extract time series information, and an attention mechanism to optimize weights. We deploy sensors to collect production measurements at a real-life cement factory for experimentation and investigate the impact of hyperparameter changes on the performance of the proposed model. Experimental results show that CNN-LSTM-A achieves a superior performance in terms of prediction accuracy over existing models such as the basic LSTM model, deep-convolution-based LSTM model, and attention-mechanism-based LSTM model. The proposed model has potentials for wide deployment in cement plants to automate and optimize the operation of decomposition furnaces.

Numerical simulation of O2/CO2 combustion in decomposition furnace

The cement industry has become the second largest source of CO2 and NOx emissions after the power industry, it is imperative to reduce CO2 and NOx emissions. O2/CO2 combustion technology can achieve CO2 enrichment and NOx reduction. As a result, its application possibilities are bright. In this article, a TTF-type decomposition furnace serves as the research object for a CFD simulation. In addition, the effects of pulverized coal combined O2/N2 and pulverized coal mixed O2/CO2 combustion on the velocity field, temperature field, material component, and NOx concentration distribution in the furnace are investigated concerning the changes of kinetic parameters of CaCO3 decomposition under different working conditions. Compared with the O2/N2 atmosphere, the temperature distribution in the high temperature zone of the decomposition furnace is more uniform under the O2/CO2 atmosphere. The temperature range is reduced in the area of extremely high temperatures. The NOx concentration at the decomposition furnace exit is reduced by 37%. The high concentration of CO2 at the output can be recycled and reused to reduce the greenhouse effect effectively. In addition, the high CO2 partial pressure increases the exit temperature by 111 K, doubles the O2 concentration, but decreases the raw meal decomposition rate from 95.9-82.2%. The process parameters must be improved to adapt to the O2/CO2 combustion technology.

Use of Nitric Acid to Control the NO <sub>2</sub> :NO <sub>X</sub> Ratio within the Exhaust Composition Transient Operation Laboratory Exhaust Stream

<div class="section abstract"><div class="htmlview paragraph">The Exhaust Composition Transient Operation Laboratory<sup>TM</sup> (ECTO-Lab<sup>TM</sup>) is a burner system developed at Southwest Research Institute (SwRI) for simulation of IC engine exhaust. The current system design requires metering and combustion of nitromethane in conjunction with the primary fuel source as the means of NO<sub>X</sub> generation. While this method affords highly tunable NO<sub>X</sub> concentrations even over transient cycles, no method is currently in place for dictating the speciation of nitric oxide (NO) and nitrogen dioxide (NO<sub>2</sub>) that constitute the NO<sub>X</sub> mixture. NO<sub>X</sub> generated through combustion of nitromethane is dominated by NO, and generally results in an NO<sub>2</sub>:NO<sub>X</sub> ratio of < 5 %. Generation of any appreciable quantities of NO<sub>2</sub> is therefore dependent on an oxidation catalyst to oxidize a fraction of the NO to NO<sub>2</sub>. Presented within this manuscript is a method for precise control of the NO<sub>2</sub>:NO<sub>X</sub> ratio within the ECTO-Lab exhaust stream by using nitric acid as the NO<sub>X</sub> precursor molecule in lieu of nitromethane. While decomposition of nitromethane generates NO as the dominate component of the NO<sub>X</sub> mixture, nitric acid decomposition produces primarily NO<sub>2</sub>. The method described herein entails metering a 70 % aqueous nitric acid solution into an upstream decomposition furnace prior to injection into the ECTO-lab exhaust. By use of nitric acid as the precursor NO<sub>X</sub> molecule, and precisely controlling the conditions at which decomposition of nitric acid occurs, the ECTO-Lab may be used as a platform to evaluate catalytic activity in absence of a diesel oxidation DOC, coming one step closer to a full engine simulator. In this study, concentrations of NO<sub>2</sub> well in excess of the theoretical thermodynamic equilibrium value were achieved by specifying the residence time and temperature of the nitric acid within the decomposition oven.</div></div>

Grey Correlation Analysis of Factors Affecting Nitrogen Oxide Concentration in Cement Production Process

Nitrogen oxides (hereinafter referred to as NOx) is one of the main pollutants produced in cement production. There have been many studies on the mechanism of NOx formation, but there is little research on the relationship between production control factors and NOx concentration. In this paper, several parameters of the formation of nitrogen oxides (decomposition furnace link and rotary kiln link) were selected by the gray correlation analysis method as the comparison sequence, and the NOx concentration was selected as the reference sequence for correlation analysis. The final results show that the parameters of the kiln tail chamber, the temperature of the decomposition furnace, and the amount of raw material discharged have the most significant effect on the NOx concentration. The research results can provide theoretical guidance for the coordinated control of cement production in the later stage, and reduce the NOx concentration under the premise of ensuring the quality of cement clinker, so as to reduce the denitration cost of enterprises by reducing the amount of ammonia water used, so as to achieve the ultimate goal of energy saving.

Study on Pyrolytic Furnace for Medical Wastes

This paper introduces a kind of removable pyrolytic furnace for the medical wastes based on the combined methods of thermal decomposition and combustion. Use the environmental protection design to minimize the pollution and the secondary pollution. Due to many infectious medical wastes cannot be transported, and must be solved locally, so infectious waste thermal decomposition furnace emerges as the time requires. Based on the thermal decomposition principle to decompose the organic, before combustion, the garbage should be carbonized first, so the original structures of polymer can be destructed, and be transformed into low molecular compounds. Heat it by heating resistance after gasification so it can continues to burn, this can decompose the dioxin and prevent the synthetic of dioxin at the largest degree. Its differential to other equipments is that it using the electric energy, the thermal decomposition furnace is internal of the incinerator in structure, which plays the effect of energy saving, so it is energy conservation and environmental protection. It is easy to install and convenient to use.

Gas-Solid Reaction Properties of Fluorine Compounds and Solid Adsorbents for Off-Gas Treatment from Semiconductor Facility

We have been developing a new dry-type off-gas treatment system for recycling fluorine from perfluoro compounds present in off-gases from the semiconductor industry. The feature of this system is to adsorb the fluorine compounds in the exhaust gases from the decomposition furnace by using two types of solid adsorbents: the calcium carbonate in the upper layer adsorbs HF and converts it to CaF2, and the sodium bicarbonate in the lower layer adsorbs HF and SiF4and converts them to Na2SiF6. This paper describes the fluorine compound adsorption properties of both the solid adsorbents—calcium carbonate and the sodium compound—for the optimal design of the fixation furnace. An analysis of the gas-solid reaction rate was performed from the experimental results of the breakthrough curve by using a fixed-bed reaction model, and the reaction rate constants and adsorption capacity were obtained for achieving an optimal process design.

Design of Control System Based on PLC for Polycrystalline Silicon Decomposition Furnace

It requires high security for useing silane decomposition reaction to produce the polycrystalline silicon. For this reason, the paper introduces the central facilities of the polycrystalline silicon production, and bases on production process, to devise a control system which combines PLC and industrial ethernet technology. The system controls temperature and pressure of the decomposition furnace, cooling water system, and production process. The practical result showes that the system is reliable and steady. It meets the requirements of process.

FAILURE ANALYSIS OF PIPES IN RADIATE SECTION OF ETHYLENE CRACKING DECOMPOSITION FURNACE INDUCED BY SULFURIZATION

Article FAILURE ANALYSIS OF PIPES IN RADIATE SECTION OF ETHYLENE CRACKING DECOMPOSITION FURNACE INDUCED BY SULFURIZATION was published on December 1, 2002 in the journal Corrosion Reviews (volume 20, issue 6).

99/00274 Method and apparatus for recovering thermally decomposed gases from waste thermal decomposition furnace

99/00274 Method and apparatus for recovering thermally decomposed gases from waste thermal decomposition furnace

Thermal decomposition furnace of waste tires

Thermal decomposition furnace of waste tires

4565138 Thermal decomposition furnace of waste tires

4565138 Thermal decomposition furnace of waste tires

4565138 Thermal decomposition furnace of waste tires : Yoshihiko Ueda, Ikuo Saito, Kazumasa Sakae, Tetuo Oogiri, Chiba, Japan assigned to Onoda Cement Co Ltd

4565138 Thermal decomposition furnace of waste tires : Yoshihiko Ueda, Ikuo Saito, Kazumasa Sakae, Tetuo Oogiri, Chiba, Japan assigned to Onoda Cement Co Ltd

Carbon from carbon monoxide disproportionation on nickel and iron catalysts: Morphological studies and possible growth mechanisms

Carbon was prepared by disproportionation of CO; Ni(CO) 4 or Fe(CO) 5 was fed to the CO stream before it entered the decomposition furnace. Electron microscopy reveals differences in the carbons obtained: adding Fe(CO) 5 resulted in the usual fibrilar growth whilst Ni(CO) 4 gave rise to spherical shells and sausage-like forms which are hollow inside. X-ray powder diffraction shows that the carbon obtained using Ni(CO) 4 is not as well organised as the carbon obtained using Fe(CO) 5. Possible formation mechanisms are discussed; very likely, the carbon shells obtained using Ni(CO) 4 are precipitated from solution in nickel whereas carbon obtained in the presence of iron is catalytically recrystallised by an iron carbide. A mechanism for the formation of helical fibres is suggested.